Matic electric inc



July 10, 1928. 1,676,469

' J. wlcKs AUTOMATIC- mnnrnonn sw'ma Filed Junq 10, 1925 3 heats-Sixeet 1 01m Jnhcks July 10, 1928.

J. WICKS AUTOMATIC TELEPHONE SYSTEM Patented July it), 1928.

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JOHN WICKS, OF'OAK PARK, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO AUTO- MATIC ELECTRIC INC, OF CHICAGO, ILLINOIS, A CORPORATION OF DELA'WARE.

AUTOMATIC TELEPHONE SYSTEIlCE.v

Application filed June 10, i825.

The present invention relates to automatic telephone systems in general, but is concerned more .particularly with telephone systems including so-called private automatic exchanges; and the principal feature of novelty resides in the provision of an efficient arrangement for interconnecting a private automatic exchange and one or more manual exchanges by means of trunk lines having subscribers stations thereon.

One object of the invention the provision of a suitable circuit arrangement for utilizing the intermittent ringing current supplied at the P. A. X. for signaling called subscribers to control the transmission of a single long application of ringing current to a-trunk line leading to a manual oflice when the manual office is called from the private automatic exchange.

It is a further object to accomplish the above result by means of a counting arrangement positive in action and controlled over the regular intermittent ringing lead.

Another object is the provision of the circuit arrangements whereby the application of ringing current is terminated upon the response of the operator.

There are other objects and features of the invention which will become apparent upon a perusal of the following description.

Referring now to the accompanying drawings comprising Figs. 13, in order for the drawings to be understood best, Fig. 2 should be placed to the right of Fig. 1 and Fig. 3 should be placed above Fig. 2. lVhen laid out in this manner these drawings represent a manual exchange shown in Fig. 1 and abbreviated as M. X. and a private automatic exchange shown in Figs. 2 and 3 and abbreviated P. A. X., together with the trunk line TL interconnecting the two exchanges.

Referring now to Fig. 1, this drawing shows a standard magneto telephone substation A and the associated line which terminates at manual exchange M. X. in the jack J. The trunkline TL terminates 'in the jack J. his drawing shows also the cord circuit CC for interconnecting the jacks J and J andother'jacks (not shown). The cord circuit is provided with an auxiliary head set HS and a calling'device CD, which are, of course, common to the cord circuit Serial No. 36,069.

CC and to the other cord circuits (not shown).

"he substations A and A, connected across thetrunk line TL are similar to the substation A.

Fig. 2 shows the connector C in the P. A. X. which is operated over the trunk line TL from the manual exchange M. X. to extend a connection to any one of the lines terminating in the P. A. X. This connector switch is of the usual vertical and rotary type, having bank contacts arranged in horizontal rows or levels. From a circuit stand point this connector is of the well known two wire type, its particular method of control being a simplcxcontrol over the two sides of the trunk line TL in parallel.

Fig. 3 shows the automatic substation A together with the associated line which terminates at the P. A. X. in the line switch LS. The line switch LS is of the well known rotary non-restoring type, having wipers 209-211, which are advanced upon the restoring stroke of the stepping magnet 208.

The connector 0, accessible to the line switch LS, is similar to the connector C, Fig. 2 except that, being a local connector, it is less complicated on account of the fact that it is not associated with a two-way trunk, and it is further simplified in that it does not have the arrangement found in the connector C for translating the interrupted ringing current into a single application.

Although only one manual exchange is shown, it is to be assumed that there is at least one other manual exchange accessible from the P. A. X. over trunk lines similar to the trunk line TL.

The trunk line TL is accessible to the connector C in the 0 level of bank contacts. It is assumed that there is at least one other trunk line such as TL connecting the manual exchange M. X., Fig. 1, with the private automatic exchange and that this trunk line is associated with a connector similar to C and is also reached from the 0 level of bank contacts. t is assumed further that the other trunk line between the manual exchange M. X. and the private automatic exchange P. A. X. also has a number of substations similar to A and A" connected therewith. From this it will be of the trunk lines between the M. X. and.

the P. A. X. should know the number of the trunk line of the desired subscriber; That being the case the trunk lines TL, etc., appear in the banks of the connectors in the same manner as ordinary subscribers lines, and the connectors are not arranged to rotate over busy trunk lines in search of an idle one in case the one called is busy, as this would result in a connection to the wrong line in case a connection is wanted to one of the intermediate substations, such as A and 11*.

On account of the fact that the connectors are not required to supply talking battery in the direction of the called substation on calls extended over the trunk lines such as TL, the'connect'or C is provided wit-h a cut-oil relay 2.3 which operates on calls to the tenth level of the connector banks to cut off the back bridge impedance222. The cut-oti' relay 10 1 of the connector C, which operates when the trunk line TL is seized to cut oil the back bridge relay 105, also operates on calls over the trunk line TL and throiigh the tenth level of the connector C to cut oil" the back bridge relay and to by pass the talking condensers 117 and 118.

The invention having been described generally, a detaileddescription oi the operation of the apparatus shown will now be given. For thispurpose it will be assumed that the subscriber at substation A in the manual exchange M. X., Fig. 1, desires to converse with the subscriber at substation A in the private automatic exchange P. A. X., Fig. 8.

The subscriber at substation A operates his hand generator thereby projecting ringing current over his line to operate the drop 2 at the operators switch-board, after 'which the subscriber removes his receiver, thereby connecting up the receiver, and energizing the transmitter from the local battery.

hen the operator notes the'operated condition of the drop 2, she inserts the plug of an idle cord circuit, for example, the ilug P of the cord circuit CC, into the jack J, thereby cutting off the drop 2. The operator now throws her combined listening and ringing key K into "listening'position, thereby connecting her listening set tothe talking strands associated with the plug P. The operator now conve'rses with the calling subscriber and ascertains the number of the desired subscriber.

Upon learning that the subscriber at sub station A", Fig. 3, is the one desired, the operator restores her key K and inserts the plug P into a jack associated with anidle one at the trunk lines, connecting the exchange M. X. totheexchange 'P. A. X.. for example, the jack J, thereby cutting off the drop 5. It will be noted that the insertion of the plug P into the jack J places battery, obtained through the two right-hand windings of the repeating coil of the cord circuit CC in multiple, on the talking conductors oi the trunk lineTL. A cco aflingly, the battery potential is extended over the two conductors at the trunk line TL and through the left-hand windings of the repeating coil associated with the connector C in multiple and the resting contact and ar mature 133 to line relay 100 ot' the connector C. Line relay 106 accordingly energizes, and at armature 141 closes a circuit for release relay 107. Release relay 107 now onergizes and at armature 1 1 1 prepares the switch for operation; extends ground to armature 149 of relay at armature 143; and at armature 142 disconnects release trunk conductor 172 from cut-ofi' relay 104 and connects it to the ground instead, there by preparing locking circuits forrclays 109 and 112, and making the trunk TL busy to the connectors.

In the manual exchange, theoperator now throws her calling device key K thereby disconnecting the battery through the resistance 1 from the right hand windings 'ot the repeating coil and substituting battery through the common'ca'lling deviceGD.

The operator now manipulates her calling device CD in accordance with the first digit oiithc desired number, thereby opening the circuit of 'line relay 106 of the connector C a corresponding number of times.

Each time its circuit is opened, line relay 100 falls back and at armature l -i1 closes 1: circuit through armature 144: and its "worle ing contact for vertical magnet 121, the circuit at the time of the first closure including the contact and oil normal spring120, series relay 108, and vertical magnet 121. By'thc operation of vertical magnet 121, the wip ers 159161 are raised opposite the desired level or bank contacts. Relay 108 is energized in series With vcrticalfmagnet 121 and being slow acting maintains its armature 145 attracted throughout the vertical movement, thereby maintaining its own circuit and that of the vertical magnet intact after the off normal springs shift as they do upon the first vertical step.

At the end of the vertical movement, relay 108 falls back and at armature 145 shifts the operating conductor from the vertical magnet to the rotary magnet.

hen the calling operator dials the next and last digit in the desired number, the corresponding series of impulses is. trans mitted through armature 145a'nd its resting contact, resting contact and armature 150, and armature 157 and its resting contact to the rotary magnet 122. Accordingly magnet 122 operates to rotate the Wipers 15916l step-by-step into engagement with the bank contacts 162164 associated with the line ofthe substation A Relay 111 is energized in multiple with rotary magnet 122 and, being slow acting, maintains its armature attracted throughout the rotary movement. Atits armature spring 152, relay 111 disconnects test wiper 160 from the test winding of relay 112 and connects itinstead to the busy relay 110, and at armature 153 places a shunt around the resting contact and armature 150 so as to maintain its own circuit and that of the rotary magnet 122 intact during the rotary movement in case busy relay energizes because 01 test wiper 160 passing over busy test contacts.

At the end of the rotary movement, the busy relay 110 is energized incase the called line is busy,- and it'is deenergized in case the called line is idle. Assuming first that thecalled line is busy, busy relay 110 is energized through test wiper 160, and, when the slow, acting relay 111 falls back, a locking circuit for busy relay 110 is closed which includes the working contact and armature 1143, armature 149 and its working contact, and the normally closed contacts controlled by armature 152. Accordingly, relay 110 remains locked up and the further operation of rotary magnet 122 is prevented at armature 150. Also the common bnsy signaling conductor 176 is connected at armature 151 to the lower heavy talking conductor to inform the calling operator that the desired line is inaccessible for the time being.

Assuming now that the desired line is idle when called, busy relay 110 is not energized when the wipers of the connector C come to rest on the bank contacts 162164. In this case, when relay 111 falls back it completes at armature 152 a circuit for theupper windingot relay 112 as follows: from ground by way of the working contact at armature 143, armature 149 and its resting contact, upper winding of relay 112, resting contact and armature 152, test wiper 160,- bank contact 163, conductor 169, relay 201 of the line switch LS, and stepping magnet 208 to battery. Relay 201 energizes over this circuit, but it is unable to operate completely owing to the mechanical interlocking arrangement (not shown) between its armature proper and that :of the unoperated line relay'202. Accordingly, all the resting contacts of relay 201'are opened, but none of the working contacts are closed, with the result that line relay 202 and-ground are disconnected from the called line, but the wipers oi the switch are not connected up. I

In the connector C, switching relay 112 energizes over the above traced circuit and closes at armature 156 a self locking circuit from the grounded conductor 172 through its lower winding; disconnects rotary magnet 122 and relay 111 at armature 157; places direct ground on test wiper 160 at armature 155; and at armature 154 and. 158 connects up the wipers 159 and 161 whereupon ringing current from the ringing lead 175 is intermittently projected out through the upper winding of ring cut-off relay 109, through wiper 159 to. ring the bridged bell at substation A and it returns through wiper 161 to ground at armature 148 and its resting contact.

When the subscriber at substation A re sponds to the ringing of his bell by removing his receiver, ring cut-off relay 109 pulls up and closes at armature 147 a locking circuit for its lower winding and at armaturcs 146 and 148 disconnects wipers 159 and 101 from its own upper winding and ground and extends them instead through armatures 135 and 137 to the windings of the back bridge relay 105, and also, of course, to the talking circuit. Back bridge relay 105 now pulls up over the called line, but its operation at this time is merely incidental and it therefore acts only in its capacity as a battery feed impedance. Although at this time there is connected parallel with the upper winding of 105 a series circuit including the relays 101 and 104, this circuit is of no effect due to the high resistance of those relays.

The talking connection is now complete and the subscribers at substations A and A may now converse with each other in any manner desired.

When the conversation is terminated, the two subscribers replace their receivers. The replacing of the receiver at substation A results merely in the deenergization of back bridge relay 105 of the connector C.

When the receiver is replaced at substation A, the subscriber thereat turns his hand generator in order to operate the drop 8 in the cord circuit CC. This operation serves to attract the attention of the operator who pulls down "the connection.

Responsive to the removal of the plug P from the jack J relay 106 of the connector 0 falls back and opens the circuit of the slow acting release relay 107 at armature 141. Relay 107 falls back after an interval and at armature 142 breaks the locking circuit of relays 109 and 112 whereupon these relays fall back. Atarmature 144 relay 107 completes a circuit through the off normal contacts for release magnet 119, with the resultthat the connector O is restored to its normal position in the usual manner.

Considering now a calltrom the substation A to the switchboard of the operator in the manual exchange M. X., Fig. 1, it will be assumed that the subscriber at substation A desires to converse with the sul scriber at substation A, Fig. 1. Accordingly, the subscriber at substation A" removes his receiver and dials the number assigned to theitrunk line TL.

loo

W'hen the receiver is removed at substation A, line relay 202 of the line switch LS pulls up over the calling line and closes at armature 206 a circuit for switching relay 201 wipers are standing in case this trunk is idle.

However, in case the trunk is busy, relay 201 is short circuited and does not energize. In this latter case the self-interrupting magnet 208 is operated over test wiper 210 to advance the wipers 209- 211 step by step in search of an idle trunk.

Assuming that the trunk comprising conductors 212-21 1 isthe first one found to be idle, stepping magnet 208 ceases to operate when this trunk is reached, and switching relay 201, being no longer short circuited, pulls up in series with magnet 208 which magnet, however, is unable to operate at this time on account of the relatively high resistance 0!? relay 201. Upon energizing relay 201 opens the test circuit and prepares the holding circuit at armature 20 1, and at arn'iature 203 and 205 extends the calling line through wipers 209 and 211, and con ductors 212 and 2141 to the line relay 221 01 the connector C. Line relay 221 now pulls up over the calling line and closes at armature 251 a circuit for release relay 224i. ielay 22 1 now energizes and closes the usual circuits at armatures and 256, and at armature'25 l grounds the release trunk conductor213, thereby establishing the usual holding circuit for the line switch LS before the slow acting line relay 202 has had time to fall back. 7

The calling subscriber now dials the first digit 0 in the desired number. The dialing of the first digit 0 results in the circuit of relay 221 of the connector C being interrupted ten times. Each time its circuit is interrupted, relay 221 falls back and closes at armature 251 a circuit for vertical magnet 231, the circuit at the time of the first closure being through armature 256 and its working contact, contact and off normal spring 233, series relay 225, and vertical 231 to battery. The operation of relay 225 and oil normal spring 233 in shifting the impulse circuit from the vertical magnet to the rotary magnet is the same in this case as in the case of the connector C. Also, the operation of the vertical magnet 231 results in this case, as before, in the wipers being raised opposite the desired level of bank contacts.

\Vhen thecalling subscriber dials the second and last digit in the number, the impulses of current are transmitted through the resting contact and armature 262, and armature 268 and its resting contact to rotary magnet234, which is connected in multiple with the slow acting relay 228. By the operation of magnet 234 the wipers 271-27 3 are rotated step by step until they come into engagement with the bank contacts 27727 9 associated with the trunk line TL. Relay 228 is energized in multiple with retary magnet 234 so as to bring about the operation of the busy relay 227 in case the line is busy and to bring about the operation of relay 229 in case the line is idle. Assuming the trunk line TL to be idle, the deenergization of relay 228 at the end of the rotary movement results in the closure of a circuit as follows: from ground by way of the working contact and armature 255 of release relay 224, armature 261 and its resting contact, upper winding of relay 229, resting contact and armature 264, test wiper 272, bank contact 278, conductor 172 leading t-o-the connector C, Fig. 2, armature 1412 and its resting contact, and cutol'l relay 104 to battery. Relay 10 1 energizes over this circuit and cuts off the back bridge relay 105 at armatures 135 and 137, at the same time connecting up the alternating-current relay 103 at armature 136 which relay 103 is now connected in a bridge across conductors 171 and 173 which is closed through condenser 116, relay 103,

working contact and armature 136, and arm at-ure 132 and its resting contact.

In the connector C, relay 229 pulls up over the above traced circuit; closes a locking circuit for its lower winding at armature 268; grounds test wiper 272 at armature 267; cuts off magnet 234 and relay 228 at armature 269; and at armatures 266 and 270 connects up the wipers 271-273.

Assoon, after the above operation "of relay 229, as the interrupter relay associated with the generator G operates to lace ringing current on conductor 175, t e ringing current is transmitted through the upper winding of relay 226 and out over wiper 271 to conductor 171. This ringing current passes through the two right-hand windings of the repeating coil associated with the connector C in series and it returns to ground over conductor 173, and through wiper 273, and armature260'and its :resting contact. The passage of this current through the right-hand windings :ofythe repeating coil results in ringing-current going out over the trunk line TL from the lefthand windings.

The alternating current relay 103, which is connected in a bridge of conductors 1711 and 173 is operated by the ringing current and it closes at armature 134 a circuit through armature 127 and its resting contact for the upper winding of relay 105. Relay 105 now energizes and locks its upper winding to ground through the working contact and armature 1355, relay 101,

normally closed contacts controlled by armature 131, left hand contact and spring 113, resting contact and armature 142 and the grounded private normal conductor 172. This locking circuit is not called into play at this time on account of the ground potential supplied to upper winding of relay 105 over its initial circuit. Relay 105 also shunts the resting contact and armature 132 of relay 102, at armature 139.

hen the ringing current is next removed by the interrupter relay associated with the generator G. Fig. 3, relay 103 falls back and opens the initial circuit of the upper winding of relay 105 whereupon the locking circuit through armature 138 and through relay 101 becomes effective. Accordingly, re-

lay 105 remains energized and relay 101 energizes; disconnects armature 13% from relay 105 and connects it instead through the normally closed contact-s controlled by armature 130 to relay 102; and. at armaturcs 126 and ,12S-disconnects the right-hand windings of the repeating coil from conductors 171 and 173 and connects them to the noninter rupted ringing conductor 174 and ground, respectively, at the same time removing ground from armature 1 11 of relay 106.

Accordingly, during the entire silent period in the l. X. ringing current is projected out over the trunk line TL to operate the bridged drop 5 associated with the jack J. It will be understood that the voltage of the generator G is likely to be much higher during this period than during the regular ringing period on account of the fact that the voltage is likely to be lowered during the regular ringing period in case several local lines are being signalled simultane ously. I

Upon the .neXtenergization of the interrupter relay associated wth the generator G. F the alternating current relay 103 of the connector C is operated again and it closes at this time a circuit for relay 102 at armature 131 through armature 127 and its working, contact and through the nor mally closed contacts controlled by armature 1301 Accordingly relay 102 energizes and closes a locking circuit for itself at armature 130, at the same time opening its initial circuit; breaks the initial circuit of relay 101 and closes a new circuit for this relay and for the upper winding of relay 105 which includes the working contact and armature 13%, armature 127 and its working contact and armature 131 and its working contact; opens at armature 132 the con-nection. between relay103 and conductor 173, leaving this connection intact through armature 139 and its working contact of the locked up back bric ge relay 105; disconnects relay-103 at armature 133; and at armature 129 shunts the condenser 116, Whereuponthe ring-cut-otf relay 226 of the connector C pulls up in series with relay 103 and disconnects the wipers 271 and 273 from ringing current and from ground. respectively, and connects them to the talking circuit. Also. since the 0 level shalt springs have been closed, upon the raising of the wipers oi the connector C opposite the tenth level, cut-off relay 223 is energized in multiple With the locking winding of ring-cut-otf relay 226. At armatures 252 and relay 223 cuts ofi back bridge relay 222. In the connector C relay 103 being no longer included in an energizing circuit due to the operation of relays 226 and 223 of the connector C falls back and opens the circuit of relays 101 and 105 at armature 13 1-. When this occurs relays 101 and 105 fall back and relay 101 removes the ringing current from the right-hand repeating coil windings.

Upon noting the operating condition of the drop 5, the operator in the manual exchange M. X., Fig. 1, inserts a plug of an idle cord circuit, for example, the plug P of the cord circuit CC into the jack 5, thereby cutting off the drop 5. It will be noted that line relay 106 of the connector 0 is not operated at this time owing to the fact that it is disconnected at armature 133 of relay 102. t

The operator now converses with the calling subscriber, and when she learns that he desires'to converse. with the subscriber at substation A, she throws her ringing key K a number of times corresponding to the particular code assigned to the substation A, for example, three rings followed by three other rings after a pause.

lVhen the subscriber at substation A removes his receiver, the conversation may proceed in the usual manner.

When the conversation is terminated, the two subscribers replace their receivers.

hen the receiver is replaced at suhsta tion A the subscriber thereat turns his hand generator so as to operate the drop 1 on the right hand side of the cord circuit CC. Upon observing the operated condition of this drop the operator pulls down the connection.

N hen the receiver is replaced at substation A Fig. 3, line relay 221 of the connector C fallsback and opens the circuit of release relay 224 at armature 251. Release relay 224now falls back and removes ground from conductor 213 at armature 25%, whereupon relays 226 and 229 fall back. When relay 229 falls back it removes ground from test wiper 272 and consequently from conductor 172. When this occurs the locked up relay 102 of the connector C and the cut off relay 10st 12111 back.

In the connector C,-as a further result of the deenergization of release relay 221, the usual release magnet circuit is closed at armature 236 through off normal cont-acts 232, with the result that the connector switch is released to its normal position in the usual manner.

Considering now again the call just completed, no mention was made of the operation which occurs in case the operator responds immediately to the operationot' the drop 5 and does not wait for the cessation of the ringing current when it is automatically cut off in the P. A. as above described. It will be noted that relay 106 of the connector C is not disconnected until relay 102 pulls up near the end of the application of the ringing current and cuts oif relay 106 at armature 133 as hereinbei'orc pointed out. Accordingly, in case the operator plugs in subsequent to the operation of relay 101 and before the operation of relay- 102, relay 106 operates and shunts condenser 116 at armature 1410, but it is not able to operate relay 107 at armature 1 11 owing to the previous operation of armature 128 of relay 101.

When the condenser 116 is shunted, relay 103 energizes in series with the upper winding of ring-cut-off relay 226 or the connector C and closes at armature 134 a circuit through armature 127 and its working contact to operate and lock up relay 102 as hereinbefore described, whereupon the operation of armature 140 is taken over at armature 149 and relay 106 falls back on account of the fact that it is cut off at armature 133.

As soon as ring cut-otf relay 226 and relay 223 of the connector C operate in the manner hereinbefore described, relay 103 falls back and permits relays 101 and 105 to fall back whereupon relay 101 falls back and disconnects the ringing current from the associated trunk line in the hereinbefore described manner.

As above pointed out, ground is not disconnected from armature 141 of relay 106 oi the connector C until relay 101 pulls up to apply ringing current from lead 17 l. It is considered practically impossible, however, (due to the promptness of the response of relay 101) for the operator to respond to the ringing current prior to the energization of relay 101 and to thereby energize relay 106 to bring about the energization of relay 107. Accordingly no attempt has been made to disconnect the ground from armature 1 11 or to take any other precautions prior to the operation of relay 101.

It will be noted that when a call is made from the P. A. X. to lWI. X. over the toll line TL, the operator may complete the conmotion to a local subscriber such as the subscriber at substation A in case that subscriber is wanted. It will be noted that the connector C is provided with 0 level shaft springs to connect the cut-off relay 104 in and means associated with said line and is sponsive to the intermittent current applied to said lead to apply ringing current to said line from another source.

2. In a telephone system, a line, means for seizing said line and for connecting a. ringing lead therewith, means for applying ringing current intermittently to said lead, and means associated with said line and responsive to the intermittent current applied to said lead to make a single application of ringing current to said line.

3. In a telephone system, a line, means for seizing said line and for connecting a ringing lead therewith, means for applying ringing current intermittently to said lead, and means associated with said line and responsive to the intermittent current applied to said lead to make a single application of ringing current to said line of a length governed by the length of the interval; elapsing between successive applications of ringing current to said lead. a

4. In a telephone system, a line, means for seizing said line and for connecting a ringing lead therewith, means for applying ringing current intermittently to said lead, means associated with said line and responsive to the intermittent current applied to said lead to make a single application of ringing current to said line of a length approximately equal to the length of the inter.- val elapsing between successive applications of ringing current to said lead.

5. In a telephone system, a line, means for seizing said line and for connecting a ringing lead therewith, means for applying ringing current intermittently to said lead, and means associated with said line and responsive to the intermittent current applied to said lead to make single application of ringing current to said line of a length substantially greater than the length of a single application of ringing current to said lead.

6. In a telephone system, a line, means for seizing said line and for connecting a ringing lead therewith, means for applying ringing current intermittently to said lead, and means associated with said line and responsive to the intermittent current applied to said lead to apply ringing current to said line during one silent period and during an adjacent ringing period.

7. In a telephone system, a line, means ill? lot;

for seizing said line and for connecting a ringing lead therewith, means for applying ringing current intermittently to said lead, and counting mechanism for applying ringing current to said line responsive to the ringing current applied to said lead.

8. In a telephone system, a line, means for seizing said line and for connecting a ring ing lead therewith, means for applying ring-- ing current intermittently to said lead, and counting relays controlled by the application of ringing current to said lead to apply ringing current to said line.

9. In a telephone system, a line, means for seizing said line and for connecting a ringing lead therewith, means for applying ringing current intermittently to said lead, counting relays controlled by the application of ringing current to said lead to apply ringing current to said line, and another counting relay to terminate the application of ringing current to the line.

10. In a telephone system, a line, means for seizing said line and for connecting a ringing lead therewith, means for applying ringing current intermittently to said lead, means associated with said line and responsive to the intermittent current applied to said lead to apply ringing current to said line, and means controlled by a response on said line to terminate the application of ringing current thereto.

11. The method of setting up a telephone connection which consists in automatically selecting one ofa plurality of lines and extending a connection to that line, in sig nalling an operator at the distant end thereof automatically responsive to the establishment of the connection, and in manually applying ringing current to said line at the distant end of said line to signal a subscriber thereon.

12. In a telephone system, a plurality of lines, a trunk line, a connector switch for connecting with a line or with said trunk line, a ringing machine, means associatedwith said connector for connecting said machine intermittently to any connected line, each ringing period being followed by a silent period, and means eliective when the connected line is said trunk line for connecting the ringing machine to the line during the silent period following the first ringing period.

13. A system as set forth in claim 12, in which the means for connecting the ringing current to the line during the silent peric is actuated responsive to ringing current r ceived in the first ringing period and is deaetuated responsive to ringing current received in the second ringing period.

14. In a telephone system, lines, another line, means for connecting with any line, antomatic ringing apparatus for intermittently signalling any line connected with, and

means associated with said other line and responsive to ringing current in the first ringing period after the line is connected with for applying ringing current to the line over a different path as soon as the said ringing period is over. I

15. In a connector switch, a ring out ofi relay having two windings, one included in the ringing circuit and the other being a locking winding, a back bridge relay, a out 01f relay for disconnecting said back bridge relay, and oil normal springs operate c responsive to a particular setting of said connector for connecting said out off relay in parallel with the said locking winding of said ring out oif relay.

16. In a telephone system, a line, means for cyclically applying ringing current to said line, each cycle consisting of a ringing period followed by a silent period, and means in the line operated responsive to the first application of the ringing current to establish a circuit for applying ringing current to said line during the entire following silent period.

17. In a telephone system, a line, means for cyclically applying ringing current to said line, each cycle consisting of a ringing period followed by a silent period, and means in the line operated responsive to the first application of the ringing current to establish a circuit for applying ringing current to said line during the following silent period, and responsive to the next application of ringing current for rendering said first mentioned means ineffective.

18. In a telephone system, a line, means for cyclically applying ringing current to said line, each cycle consisting of a ringing period followed by a silent period, and means in the line operated responsive to the first application of the ringing current to establish a circuit for applying ringing current to said line during the following silent peri 0d, and responsive to a subsequent applica tionof ringing current for rendering said first mentioned means I ineffective.

19. In a telephone system, a line, means for cyclically applying ringing current to said line, each cycle consisting of a ringing period followed by a silent period, and means in the line operated responsive to the first application of the ringing current to establish a circuit for applying ringing currentto said line during the following silent period, and responsive to the next application of ringing current, or to the prior answering of the call, for rendering said first .mentioned means ineffective.

20. In a telephone system, a switch, a group of lines accessible to said switch, another group of lines accessible to said switch, means included in the switch for seizing line in either group, means'for periodically applying ringing current to the seized line,

and means responsive to the periodically applied ringing current to a line of the first group for causing the continued application of the ringing current for a. time substantially equal to a complete ringing cycle.

21. In a telephone system, a subscriber controlled switch having access to a number of groups of lines, means for selecting a desired line, means common to all the lines for periodically applying ringing current to said line, means responsive to the first application of ringing current associated only with. certain of the lines to cause the application of ringing current during the interval following the first application of ringing current, and means responsive to the second application of current to cause the disconnection of the second named means from the line.

In a telephone system, a subscriber controlled r-"witch. having access to a number oi" groups or lines, means for selecting a desired 1 no, means common to all the lines for periodic: lly applying ringing current to said line, means responsive to the first application of ringing current associated only with certain of the lines to cause the application of rii'iging current during the interval following the first application of ringing currei'it, and means responsive to the second application of current, or to the prior answering ol the call, to cause the disconnection of the second named means from the line.

In a telephone system, a line, a group of lines, a switch including Wipers arranged to select a desired line of said group of lines, means for periodically applying ringing current to the selected line, and means for connecting the wipers with the first line a predetermined period of time after the wipers select the desired line, said period of time being a function of the period of the ringing current.

24;. In a telephone system, a line, a group of lines, a switch including wipers arranged to select a desired line of said group of lines, means for periodically applying ringing current to the selected line, means for connecting the wipers with the first line a pre determined period of time after the Wipers select the desired line, said period of time being approximately equal to one ringing cycle.

25. In a telephone system, a line, a grow, of lines, a switch including wipers arranged to select a desired line of said group of lines, means for periodically applying ringing current to the selected line, means for con necting the wipers with the first line upon the answering of the call or a predetermined period of time after the wipers select the desired line, said period of time being approximately equal to one ringing cycle.

26. In a telephone system, a group of lines, means for calling a desired line, said means including a source of E. M. F., a source of ringing E. M. E, means for periodically applying to said lines both of said E. M. Es simultaneously followed by the first of said E. F.'s alone, means render ing said first named E. M; F. ineffective, means effective upon a subsequent application of ringing E. M. F. or upon the prioranswering of the call to render said first named E. M; F. effective, and means responsive to the first nan red E. M. It. for rendering said first named means ineffective;

527. In a telephone system, a group of lines, means for calling a desired line, said means including a source of E. M. E, a source of ringing E. M; E, means for periodically applying to said lines both of said E. M. Es simultaneously followed by the first of said E. M. F.s alone, means rendering said first named E. M. F. ineffective, means effective upon a subsequent application of ringing E. M. F. to render said first named E. M. F. effective, and means responsive to the first named E. M. F. for rendering said first named means ineffective.

In a telephone system, a line the two ends of which are in non-talking relation ship, means for intermittently applying ringing current to the line, and means responsive to the second application of ringing current or upon the prior answering of the call to render said first named means ineffective and to bring the ends of line into talking relationship.

29. In a telephone system, a line the two ends of which are in non-talking relationship, means for intermittently applying ringing current to the line, and means responsive to the second application of ring mg current to render said first named means ineffective and to bring the ends of line into talking relationship.

30. In a telephone system, a connector, 2. line accessible to the connector, means controlled by the connector for projecting ringing current over the line over either of tWo paths, one of said paths including the talking conductors of the connector and the other path excluding said'talking conductors.

31. In a telephone system, a connector, a

JOHN WICKS.

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